﻿using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;

namespace ModelValidation.Infrastructure {
    public class MustBeTrueAttribute : Attribute, IModelValidator {

        public bool IsRequired => true;

        public string ErrorMessage { get; set; } = "This value must be true";

        public IEnumerable<ModelValidationResult> Validate(
                ModelValidationContext context) {
            bool? value = context.Model as bool?;
            if (!value.HasValue || value.Value == false) {
                return new List<ModelValidationResult> {
                    new ModelValidationResult("", ErrorMessage)
                };
            } else {
                return Enumerable.Empty<ModelValidationResult>();
            }
        }
    }
}
